How does one add 192.168.100.x as a secondary alias IP?

[Manny]

I don't know whats up with that, Comcast doesn't want us to keep track of the problem.
What I am going to try is running RG6 Quad-shield, from where Comcast comes into the house to the Arris SB8200 and see what happens. here Comcast uses RG6 series cabling. Have you tried that?

 

[Almighty1]

I replied to your comment on DSLrports.com. You can read my other thread here:
https://www.dslreports.com/forum/r3...ignals-look-fine-Arris-SurfBoard-SB8200-modem

Basically, everything is new.

Tap was replaced with a new one on June 30, 2017
From tap which is in the back private street in back of house is underground drop cable using black CommScope 1.8Ghz RG-6 TriShield to the 3Ghz Grounding Block, both new replaced on July 17, 2017.
From grounding block which is in the back right corner of house, black CommScope 1.8Gh RG-6 TriShield cable which goes up to the roof and then down to the front left of the house into a 3Ghz Coupler which was replaced by Comcast on June 29, 2017.
From Coupler is a white Amphenol TFC-10 (Times Fiber Communications) sweep tested to 1.0Ghz Tri-Shield RG-6 cable that connects from the coupler directly to my modem that was installed by Comcast Business on February 18, 2016.

So basically everything is new. Quad-Shield may not actually be better than Triple or even Dual Shield as the Belden 1694A is the best cable out there that is 4.5Ghz with tight tolerances and is Dual Shield only, bluejeanscable.com has them available too.